1. Field of the Invention
The present invention relates to a fuel cutoff valve that is mounted on an upper wall of a fuel tank and opens and closes a connecting passage to connect the fuel tank and outside.
2. Description of the Related Art
On the upper part of a fuel tank, provided is a vaporized fuel processing device equipped with a full-fuel control valve and a fuel cutoff valve (roll over valve) connected to a canister, and by each valve being opened and closed at prescribed fuel fluid levels, air flow to outside the fuel tank is secured, and outflow of the liquid fuel to outside is prevented. The roll over valve cuts off fuel to outside at the fuel fluid level above the full tank fluid level to prevent fuel leakage such as when the vehicle is on a slope, when the vehicle is driving in slalom form, and the like.
However, in recent years, to deal with the varied and large space occupied in vehicles, flattening of fuel tanks has been studied, but with the kind of flattened fuel tank, to make the ratio of the dead space at the upper part of the fuel tank smaller, it is preferable to set the fuel fluid level at which the valve closes as high as possible. However, when the fuel fluid level during closing of the valve is set high, it is easy for the roll over valve to be immersed in fluid. Even in the case of the kind of fluid immersion, as shown in Japanese Pat. No. 3331269, known are means whereby to obtain high sealing properties, a rubber valve body is mounted on the center upper part of a float, and when the rubber valve plug is closing the connection path, the outer periphery of the rubber valve plug is flexibly deformed.
However, it is necessary for the rubber valve body to be rather thin so that the rubber valve body can undergo elastic deformation. The thin rubber valve body creates the problem of deterioration of the rubber valve body over time due to repeated elastic deformation.